Machines for winding coils of rolled products are known, also known as belt wrappers, used for winding a rolled product on a winding shaft or mandrel and for forming a coil.
For example, a machine for winding coils is known, which comprises a support frame, selectively movable for example on sliding guides, nearer to or away from the winding shaft.
The support frame is provided with a concave portion which partly surrounds the winding shaft during use.
At least one closing arm is hinged, with one end, to the support frame, in correspondence with the concave portion, and can be selectively taken to a first position in which it at least partly closes the concave portion, thus surrounding the winding shaft during use, and a second position where the concave portion is open. In the second position, the closing arm is taken to a condition of non-interference with the winding shaft, for example during the movement of the support frame along the sliding guides.
Guide and return rolls are installed on the support frame and on the closing arm, with axes of rotation substantially parallel to those of the winding shaft.
A belt is wound on the guide and return rolls, with a closed-ring configuration that substantially surrounds the support frame on the perimeter.
In correspondence with the concave portion of the support frame and the closing arm, a segment of belt is defined which, during use, at least partly surrounds the periphery of the winding shaft.
A tensioner device is also normally associated with the support frame, suitable to regulate the tension of the belt.
When the operations to wind the rolled product on the winding shaft are started, the support frame is translated along the sliding guides to take the concave portion of the latter into proximity with the winding shaft. In this condition, the closing arm is kept in an open position so that the belt, during translation, moves to surround the winding shaft peripherally.
In this condition the support arm is taken to its closed position so that a segment of belt surrounds a substantial part, for example at least 270°, of the circumference of the winding shaft.
In this condition, the rolled product is fed toward the winding shaft and is positioned between the external surface of the winding shaft and the belt.
The belt exerts on the rolled product a pressure suitable to keep it adherent and resting completely against the external surface of the winding shaft.
The winding shaft is made to rotate to wind the rolled product on it.
Once some spirals of rolled product have been wound, generally two to four, the friction generated between them is sufficient to allow to wind the remaining rolled product onto the winding shaft and hence to form the coil.
This solution therefore provides that the closing arm is taken to its open position and the support frame is retracted along the sliding guides to move to a condition of non-interference with the coil being formed.
Merely by way of non-restrictive example of the present invention, an aluminum rolled product with a thickness comprised between 10 mm and 20 mm is generally fed to the winding shaft at a speed comprised between 0.2 and 1.8 m/s, and generally has a temperature varying between 350° C. and 500° C. These conditions are very onerous, at least for the belt which, due to the great friction generated with the rolled product, is subject to great wear and needs frequent maintenance and replacement interventions.
The operations to replace the belt require that the operators remove substantial parts of the support frame to generate the spaces needed for the passage and installation of the belt on the guide and return rolls.
In particular, for installation the belt is supplied in its open form, for example having separated the meshes of which it is made.
Once open, the belt is inserted into the machine with one end edge in a direction substantially parallel to the direction of feed of the metal product.
The replacement operations are particularly complex and time-consuming in terms of dis-assembling and re-assembling the belt and parts of the support frame. This also entails long stoppages in production.
One purpose of the present invention is to obtain a machine for winding coils of the type described above, which allows to simplify and accelerate the maintenance operations, in particular those connected to replacing the belt.
Another purpose of the present invention is to obtain a machine for winding coils which allows to automate as much as possible the maintenance operations to be carried out on it, for example to replace the belt.
Another purpose of the present invention is to obtain a machine for winding coils which allows to use belts with a directly closed-ring structure and which therefore are not obtained by connecting their end edges. This also allows to limit the generation of surface defects on the rolled product due to its contact with the joints in the belt.
Another purpose is to perfect a method for replacing a belt in a machine for winding coils that is simple and quick.
The Applicant has devised, tested and embodied the present invention to overcome the shortcomings of the state of the art and to obtain these and other purposes and advantages.